Acidic and catalytic properties of MCM-22 and MCM-36 zeolites synthesized from the same precursors

Samples of MCM-22 and MCM-36 (the pillared MCM-22 analog), synthesized from the same precursors were characterized by various techniques: XRD, N-2 adsorption, pyridine and 2,4-diinethylquinoline adsorption followed by IR spectroscopy m-xylene transformation at 350degreesC in absence or in presence of 2,4-dimethylquinoline. The MCM-36 samples were shown to present sinusoidal channels, mesopores and/ or supermicropores containing cups but also a small amount of undesired supercages. The method previously developed to estimate the activity and selectivity of the three MCM-22 pore systems (sinusoidal channels. supercages and external cups) was adapted to the characterization of the MCM-36 pore systems. Pillaring causes a large change in the distribution of the activity: approximately 15 % of m-xylene transformation occurs in the inner micropores of the synthesized MCM-36 against more than 70 % in the corresponding MCM-22 sample. Hence, 85 % of the activity of MCM-36 (against 30 % in MCM-22) is due to the protonic sites located in cups which are accessible to bulky molecules. (C) 2004 Elsevier B.V. All rights reserved.